<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        html,
        body {
            height: 100%;
            margin: 0;
        }
        .container {
            /* height: 100%; */
            /* flex-direction: column; */
            /* display: flex; */
            /* align-items: flex-start; */
            /* background-color: red; */
        }

        /* .test {
            background-color: tomato;
        } */
        .container div {
            display: inline-block;
            vertical-align: top;
        }
    </style>
</head>
<body>
    <div class="container">
        <div style="background-color: antiquewhite;">Div 1<br/>23423<br/>23423<br/>23423<br/>23423<br/>23423<br/>23423</div><!--
        --><div style="background-color:aqua; height: 100%;">Div 2</div><!--
        --><div style="background-color: rgb(112, 132, 165); height: 100%;">Div 3<br/>werwer</div>
    </div>
</body>
</html>